Automatic headlights

Well I got bored yesterday and pulled out my box of electronics goodies. Want to get some more automation in the car so i'm gonna build some auto headlights. Seen the kits advertised for £35 but it's only a matter of a couple of components.

How it works: couple of light sensors on the windscreen monitor the light levels. When the levels drop below a certain threshold for more than 2 seconds it switches the headlights on. It then keeps monitoring and if the light goes above the threshold for 15 seconds it will turn them back off.

the light sensors are about £1 a pop and the chip i'll be using to run it cost me ~£1.50. Even after the cost of wire and solder it's only going to cost about £5/6

Parts list:
1 x LM7805 £0.82
1 x LM7833 £1.28
1 x ATTiny12 £1.27
2 x CdS sensors £0.98each
a few capacitors and resistors (once i've worked out the wiring diagram) £20p each

Won't the sensors in the windscreen sence an on coming car ? Can it progromed for longer a over riden ? Just a thought if yourdriving on the motorway you have constant flow of on coming traffic which wouldturn lights off

Good idea though I'd be interested in buying a set up if you make a batch

the oncoming traffic is the reason i'm using two sensors, put one each side. Also having the 20 second delay on turning off should help with that problem. Another thing i'm doing to help this is covering both sensors with a red filter, this will help prevent uv light being bounced around through the glass in the screen.

Can be programmed for any length of time. The ATTiny is a minature processor so could add buttons for different functions to it easily.

Tidy

1 sensor on the scuttle panel pointing directly up? so it would be in shadow of on coming cars lights

aye that's probably the plan, going to have a look tonight when i'm driving to see which areas are in shade from the headlights. want them to be fairly flush fit to wherever they mount obviously but that shouldn't be too hard, they're about 5mm square

Have this feature on the Xsara already, I keep it turned off though as it's a known cause of bulb failure on starting when it's dark (happened twice when it was on, not happened since)

nice, any idea where the sensors for yours are mounted? Will be wiring in a switch so i can turn it off for starting/other reasons.

Not sure if it's built in with the auto wiper/rain sensor on the top of the screen, never really looked into it TBH. would be simple enough to find out if you want.

had a play last night with where i want the sensors. settled on the top demister vents as then it can sit in the shade and measure ambient light without getting affected by car headlights

sweet get it done and finished by sunday is your task lol

lol, will see how busy I am tmrw. got to pick up a few more bits first. gonna draw up the wiring diagrams now tho

got all the bits together now and been monitoring resistance levels relative to light so i know where to make the change (fitting an adjuster knob too). Gonna be testing it out in the car this week

the LDR hooked up to my protoboard